DjVuFileCache.h

//C- -*- C++ -*-//C- -------------------------------------------------------------------//C- DjVuLibre-3.5//C- Copyright (c) 2002 Leon Bottou and Yann Le Cun.//C- Copyright (c) 2001 AT&T//C-//C- This software is subject to, and may be distributed under, the//C- GNU General Public License, either Version 2 of the license,//C- or (at your option) any later version. The license should have//C- accompanied the software or you may obtain a copy of the license//C- from the Free Software Foundation at http://www.fsf.org .//C-//C- This program is distributed in the hope that it will be useful,//C- but WITHOUT ANY WARRANTY; without even the implied warranty of//C- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the//C- GNU General Public License for more details.//C- //C- DjVuLibre-3.5 is derived from the DjVu(r) Reference Library from//C- Lizardtech Software. Lizardtech Software has authorized us to//C- replace the original DjVu(r) Reference Library notice by the following//C- text (see doc/lizard2002.djvu and doc/lizardtech2007.djvu)://C-//C- ------------------------------------------------------------------//C- | DjVu (r) Reference Library (v. 3.5)//C- | Copyright (c) 1999-2001 LizardTech, Inc. All Rights Reserved.//C- | The DjVu Reference Library is protected by U.S. Pat. No.//C- | 6,058,214 and patents pending.//C- |//C- | This software is subject to, and may be distributed under, the//C- | GNU General Public License, either Version 2 of the license,//C- | or (at your option) any later version. The license should have//C- | accompanied the software or you may obtain a copy of the license//C- | from the Free Software Foundation at http://www.fsf.org .//C- |//C- | The computer code originally released by LizardTech under this//C- | license and unmodified by other parties is deemed "the LIZARDTECH//C- | ORIGINAL CODE." Subject to any third party intellectual property//C- | claims, LizardTech grants recipient a worldwide, royalty-free, //C- | non-exclusive license to make, use, sell, or otherwise dispose of //C- | the LIZARDTECH ORIGINAL CODE or of programs derived from the //C- | LIZARDTECH ORIGINAL CODE in compliance with the terms of the GNU //C- | General Public License. This grant only confers the right to //C- | infringe patent claims underlying the LIZARDTECH ORIGINAL CODE to //C- | the extent such infringement is reasonably necessary to enable //C- | recipient to make, have made, practice, sell, or otherwise dispose //C- | of the LIZARDTECH ORIGINAL CODE (or portions thereof) and not to //C- | any greater extent that may be necessary to utilize further //C- | modifications or combinations.//C- |//C- | The LIZARDTECH ORIGINAL CODE is provided "AS IS" WITHOUT WARRANTY//C- | OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED//C- | TO ANY WARRANTY OF NON-INFRINGEMENT, OR ANY IMPLIED WARRANTY OF//C- | MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.//C- +------------------------------------------------------------------// // $Id: DjVuFileCache.h,v 1.9 2007/03/25 20:48:30 leonb Exp $// $Name: debian_version_3_5_22-9 $#ifndef _DJVUFILECACHE_H#define _DJVUFILECACHE_H#ifdef HAVE_CONFIG_H#include "config.h"#endif#if NEED_GNUG_PRAGMAS# pragma interface#endif#include "DjVuFile.h"#ifndef macintosh //MCW can't compile# ifndef UNDER_CE# include <sys/types.h># include <time.h># endif #else# include <time.h>#endif#ifdef HAVE_NAMESPACESnamespace DJVU {
# ifdef NOT_DEFINED // Just to fool emacs c++ mode}
#endif#endif/** @name DjVuFileCache.h Files #"DjVuFileCache.h"# and #"DjVuFileCache.cpp"# implement a simple caching mechanism for keeping a given number of \Ref{DjVuFile} instances alive. The cache estimates the size of its elements and gets rid of the oldest ones when necessary. See \Ref{DjVuFileCache} for details. @memo Simple DjVuFile caching class. @author Andrei Erofeev <eaf@geocities.com> @version #$Id: DjVuFileCache.h,v 1.9 2007/03/25 20:48:30 leonb Exp $#*///@{/** #DjVuFileCache# is a simple list of \Ref{DjVuFile} instances. It keeps track of the total size of all elements and can get rid of the oldest one once the total size becomes over some threshold. Its main purpose is to keep the added \Ref{DjVuFile} instances alive until their size exceeds some given threshold (set by \Ref{set_maximum_size}() function). The user is supposed to use \Ref{DjVuPortcaster::name_to_port}() to find a file corresponding to a given name. The cache provides no naming services */#ifdef UNDER_CEclass DjVuFileCache : publicGPEnabled
{
protected:
DjVuFileCache(constint) {}
public:
staticGP<DjVuFileCache>create(constint);
virtual ~DjVuFileCache(void);
voiddel_file(constDjVuFile *) {}
voidadd_file(constGP<DjVuFile> &) {}
voidclear(void) {}
voidset_max_size(int) {}
intget_max_size(void) const {return 0;}
voidenable(bool en) {}
boolis_enabled(void) const {returnfalse;}
} ;
#else00128class DjVuFileCache : publicGPEnabled
{
protected:
DjVuFileCache(constint max_size=5*2*1024*1024);
public: /** Constructs the #DjVuFileCache# @param max_size Maximum allowed size of the cache in bytes. */staticGP<DjVuFileCache>create(constint max_size=5*2*1024*1024);
virtual ~DjVuFileCache(void);
/** Removes file #file# from the cache */voiddel_file(constDjVuFile * file);
/** Adds the given file to the cache. It it's already there, its timestamp will be refreshed. */voidadd_file(constGP<DjVuFile> & file);
/** Clears the cache. All items will be deleted. */voidclear(void); /** Sets new maximum size. If the total size of all items in the cache is greater than #max_size#, the cache will be deleting the oldest items until the size is OK. */voidset_max_size(int max_size);
/** Returns the maximum allowed size of the cache. */intget_max_size(void) const;
/** Enables or disables the cache. See \Ref{is_enabled}() for details @param en - If {\em en} is TRUE, the cache will be enabled. Otherwise it will be disabled. */voidenable(bool en);
/** Returns #TRUE# if the cache is enabled, #FALSE# otherwise. When a cache is disabled, \Ref{add_file}(), and \Ref{del_file}() do nothing. But the {\em maximum size} is preserved inside the class so that next time the cache is enabled, it will be configured the same way. Clearly this "enable/disable" thing is for convenience only. One could easily simulate this behavior by setting the {\em maximum size} of the cache to #ZERO#. */boolis_enabled(void) const;
public:
class Item;
class Item : publicGPEnabled
{
public:
virtual ~Item(void);
time_t get_time(void) const;
GP<DjVuFile> get_file(void) const;
unsignedint get_size(void) const;
void refresh(void);
public:
GP<DjVuFile> file;
time_t time;
GPosition list_pos;
staticint qsort_func(constvoid * el1, constvoid * el2);
Item(void);
Item(constGP<DjVuFile> & xfile);
};
protected:
GCriticalSection class_lock;
/** This function is called right after the given file has been added to the cache for management. */virtualvoidfile_added(constGP<DjVuFile> & file); /** This function is called when the given file is no longer managed by the cache. */virtualvoidfile_deleted(constGP<DjVuFile> & file); /** This function is called when after the cache decides to get rid of the file. */virtualvoidfile_cleared(constGP<DjVuFile> & file);
GPList<Item> get_items(void);
private:
GPList<Item> list;
bool enabled;
int max_size;
int cur_size;
int calculate_size(void);
void clear_to_size(int size);
};
//@}inline
DjVuFileCache::Item::Item(void) : time(::time(0)) {};
inline
DjVuFileCache::Item::Item(constGP<DjVuFile> & xfile) :
file(xfile), time(::time(0)) {}
inline
DjVuFileCache::Item::~Item(void) {}
inlineGP<DjVuFile>
DjVuFileCache::Item::get_file(void) const{
return file;
}
inlineunsignedint
DjVuFileCache::Item::get_size(void) const{
return file->get_memory_usage();
}
inline time_t
DjVuFileCache::Item::get_time(void) const{
return time;
}
inlinevoid
DjVuFileCache::Item::refresh(void)
{
time=::time(0);
}
inline
DjVuFileCache::DjVuFileCache(constint xmax_size) :
enabled(true), max_size(xmax_size), cur_size(0) {}
inlinevoid00262DjVuFileCache::clear(void)
{
clear_to_size(0);
}
inlinebool00268DjVuFileCache::is_enabled(void) const{
return enabled;
}
inlineint00274DjVuFileCache::get_max_size(void) const{
return max_size;
}
#endifinlineGP<DjVuFileCache>00282DjVuFileCache::create(constint max_size)
{
returnnewDjVuFileCache(max_size);
}
#ifdef HAVE_NAMESPACES}
# ifndef NOT_USING_DJVU_NAMESPACEusing namespace DJVU;
# endif#endif#endif